Abrasive implement



Patented on. 24, 1939 UNITED STATES ABRASIVE IMPLEMENT Lawrence v.Redman, Caldwell, N. J., assignor,

by mesne assignments, to Bohr-Manning Corporation, Troy, N. Y., acorporation of Massachusetts No Drawing. Application August 19, 1927,Serial No. 214,219

6 Claims. (0151-480) This invention relates to abrasive implements,

and comprises a novel implement of this characby an infusible butnon-rigid or flexible bonding agent, which for purposes ofidentification I will term a flexible phenolic resin. The term abrasiveimplement is used broadly herein to include not only abrasive sheets,discs and other grinding and cutting tools, but also polishing wheels ordiscs, emery and sand papers and cloths I and the like. It is in theselast-mentioned ap plications, where the abrasive grain is applied to aflexible base such as paper, cloth or felt, that the advantages of myinvention are most strikingly exhibited.

Infusible and insoluble resins of the well known phenol-aldehyde typehave long been used for bonding abrasive grains for making grindingwheels and other implements. This is disclosed for example in UnitedStates Patent 942,808 to L. H. Baekeland, and United States Patent.

1,537,454 to Brock. In these cases, however, and in all prior cases ofwhich I am aware wherein resins of the phenol-aldehyde type have beenused, the object has been to provide a strong, hard, infusible, rigidbond for .the grains unless modified by high boiling solvents orplasticizers as disclosed in a prior patent to Baekeland 1,019,407,March 5, 1912, or my prior Patent 1,107,703, August 18, 1914. Both ofthese patents describe glycerine and similar modifying agents butplasticizers of this nature have a tendency to reducethe strength oradhesion of the bond to the grains in proportion to the amount of likeimplements in which the grains are bonded by glue or other substancewhich melts or softens to a tacky state at the working temperature.

It is well known that abrasive papers and cloths as heretoforeavailable, rather quickly lose their free-cutting characteristics inuse. This is due to several causes among; which are the following:

plasticizer included and to cause the resin binder 1. Under the veryconsiderable rise of temperature due to the friction between theabrasive and the work and the cutting action of the abrasive, the usualbonds soften and flow, coatin the grains. 5

2. Under the same conditions these bonds become tacky, and pick up andtenaciously hold both the abrasive dust and' the dust from the work,with the result that the interstices between the grains are soon partlyor completely filled, l0 and the initial free-cutting character is lost.

I have found that both of these difliculties can be overcome byproviding a bond which, although initially flexible, does not fuse norbecome tacky at any temperature to which the implement is 15 subjectedin use. So far as I am aware no bond having these essentialcharacteristics has been applied heretofore in the manufacture ofabrasive .implements. Prior bonding materials have either been initiallyrigid, in which case they 20 could not be applied with advantage toflexible bases: or if initially flexible they have softened unduly underworking conditions.

I have found that certain flexible phenolic resins, heretofore used ascoating compositions, 25 possess to a very remarkable degree thedesirable qualities above indicated; and that when used for bondingabrasive grains in the manufacture of abrasivepapers and cloths theyyield a product characterized in marked degree by freedom from 30tendency to fill and clog. While my invention is not limited to aparticular composition of binder I prefer to use for the purpose suchflexible phenolic resins as may be prepared, for example, by effecting areaction between tung oil and phenol in presence of a converting agentor catalyst, and further hardening the resulting phenolic complex to itsultimate infusible state with hexamethylenetetramine or othermethylene-containing or aldehyde hardening agent and suflici'entapplication of heat. For example resinous compositions well adapted forthe present purpose .may be prepared as described in Unitedstates Patent1,590,079 to Byck. But as stated above my invention .is not restrictedto the use of this particular composition, but contemplates theemployment of any equivalent composition possessing the essentialqualities of flexibility at normal as well as higher temperatures,

v the rest tend to cut or scratch the work; whereas with the flexiblebond such projecting grains yield to the pressure. and a true polishingeiiect is obtained. The polishing implement may assume various formsaccording to the character of work to be done. For example it mayconsist of an assembly of fabric discs, mounted on a central shaft, andeach coated around the peripheral portion with the abrasive grains,flexibly bonded as above described. Or it may comprise a metallic orother disc, rotatably-mounted, and provided with a heavy felt rim whichcarries the flexibly bonded abrasive. These polishing implements, likethe abrading and cutting tools described above, retain to a remarkabledegree their cificiency and free-working characteristics, owing asalready explained to the non-flowing character of the bond, and itsfreedom from tackiness at high temperatures, coupled with a m highdegree of flexibility at all temperatures.

The above-described flexible phenolic resins possess other advantages.Thus they are unaffected by water or oil, and resistant to mostchemicals, to air-oxidation, and to all common solvents. These qualitiesthey possess in common with the resinoids of the phenol-aldehyde typewhich have long been used for bonding abrasives. Like the phenolaldehyderesinoids they are infusible at any temperature. But unlike theseresinoids they are highly flexible, and hence adapted for such abrading,cutting and polishing purposes as require their attachment to a flexiblebase or carrier.

I claim:

1. As a new article of manufacture, an abrasive implement comprising aflexible base, abrasive grains, and a binder'for securing said grains tosaid base, said binder including the reaction product of a phenol withoil and a methylene-containing agent, and characterized by inherentflexibility and insolubility.

2. As a new article of manufacture, an abrasive implement comprising aflexible base, abrasive grains, and a binder for securing said grains tosaid base, said binder including a. phenol-oil resin reaction product.

3. An abrasive article comprising an undistorted composite of a sheet ofcellulosic backing material and a grit or layer of abrasive particlesand a binder uniting said particles to the backing comprising thepolymerized reaction product of a, fatty oil, a phenol and substancehaving an active methylene group soluble in the oil.

4. An abrasive article in the nature of sandpaper comprising a compositeof a sheet of cellulosic backing material and a grit or layer ofabrasive particles and a binder uniting said par- .ticles to the backingcomprising the polymerized and oxidized reaction product of a fatty oil,a phenol and a substance having an active methylene group soluble in theoil.

5. An abrasive article comprising a composite of a sheet of cellulosicbacking material and a layer of abrasive particles and a binderunitingsaid particles to the backing comprising the polymerized reactionproduct of a fatty oil, a phenol and substance having an activemethylene group.

6. An abrasive article in the nature of sandpaper comprising a compositeof a sheet of cellulosic backing material and a layer of abrasiveparticles and a binder uniting said particles to the backing comprisingthe polymerized and oxidized reaction product of a fatty oil, a phenoland a substance having an active methylene group.

LAWRENCE V. REDMAN.

